Zener diode with reduced substrate current
A Zener diode is fabricated on a semiconductor substrate having semiconductor material thereon. The Zener diode includes a first well region having a first conductivity type, formed in the semiconductor material. The Zener diode also includes a first region having a second conductivity type, formed in the first well region (the second conductivity type is opposite the first conductivity type). The Zener diode also includes a second region having the first conductivity type, wherein the second region is formed in the first well region and overlying the first region. An electrode is formed in the first region, and the electrode is electrically coupled to the second region.
1. A Zener diode comprising:
a substrate including semiconductor material having a first conductivity type;
an isolation tub located in the semiconductor material, the isolation tub having a second conductivity type, and the isolation tub generally defining a first interior volume;
a sidewall located within the first interior volume, the sidewall having the first conductivity type, and the sidewall generally defining a second interior volume;
a first region having the first conductivity type, formed in the semiconductor material, the first region located within the second interior volume;
a second region having the second conductivity type, formed in the semiconductor material and overlying the first region, the second region located within the second interior volume, wherein the second conductivity type is opposite the first conductivity type; and
an electrode formed in the second region, wherein the electrode is electrically coupled to the first region.
2. The Zener diode of claim 1 , further comprising a plug region having the first conductivity type, the plug region extending from the electrode to the first region.
3. The Zener diode of claim 1 , wherein:
the sidewall is electrically connected to the first region;
the first region is electrically connected to the plug region; and
the plug region is electrically connected to the electrode.
4. The Zener diode of claim 3 , wherein:
the sidewall physically contacts the first region;
the first region physically contacts the plug region; and
the plug region physically contacts the electrode.
5. The Zener diode of claim 2 , further comprising a third region formed in the second region, the third region having the second conductivity type, and the third region extending from the electrode.
6. The Zener diode of claim 5 , wherein the third region is electrically connected to, and physically contacts, the electrode.
7. The Zener diode of claim 5 , wherein the plug region comprises a plurality of plugs having the first conductivity type.
8. The Zener diode of claim 5 , wherein at least a portion of the plug region is flanked by the third region.
9. The Zener diode of claim 1 , wherein the Zener diode is substantially free of substrate injection current when reverse biased.
10. The Zener diode of claim 1 , wherein the first conductivity type is n-type and the second conductivity type is p-type.
11. The Zener diode of claim 1 , wherein the first conductivity type is p-type and the second conductivity type is n-type.
12. A Zener diode comprising:
a substrate including semiconductor material;
an isolation tub located in the semiconductor material, the isolation tub generally defining a first interior volume;
a first-type well region located in the semiconductor material, the first-type well region being generally configured as a sidewall located within the first interior volume, the sidewall generally defining a second interior volume;
a first-type region located in the semiconductor material, the first-type region being located within the second interior volume;
a second-type region formed in the semiconductor material, the second-type region being located within the second interior volume and overlying the first-type region;
an electrode region formed in the second-type region;
a first-type plug region extending from the electrode region to the first-type region, the first-type plug region electrically connecting the electrode region to the first-type region; and
a Zener implant region formed in the second-type region, the Zener implant region extending from the electrode region toward the first-type region.
13. The Zener diode of claim 12 , wherein the first-type plug region extends from a portion of the electrode region to the first-type region.
14. The Zener diode of claim 12 , wherein the first-type region is electrically connected to the first-type well region.
15. The Zener diode of claim 12 , wherein:
the isolation tub comprises moderately doped second-type semiconductor material;
the first-type well region comprises moderately doped first-type semiconductor material;
the first-type region comprises moderately doped first-type semiconductor material;
the second-type region comprises moderately doped second-type semiconductor material;
the electrode region comprises highly doped first-type semiconductor material;
the first-type plug region comprises moderately doped first-type semiconductor material; and
the Zener implant region comprises highly doped second-type semiconductor material.
16. The Zener diode of claim 12 , further comprising an electrode for biasing the isolation tub.